writer：YueSun,GuoTian,TaoYang,ShenglongWang,BolingLan,XuelanLi,TianpeiXu,LongJin,WeiliDeng,*andWeiqingYang*
keywords：crosslinking degree, human-machine interfaces, piezoionic effect, response time, tactile sensor
source：期刊
Issue time：2024年

Ionic hydrogels are uniquely suited as force-sensing layers because of

their good biocompatibility and controlled electromechanical properties. The

emerging piezoionic effect allows them to sense the position of pressure, but

the low response rate limits their applications. Herein, this work focuses on

modulating the response time of piezoionic outputs through crosslinking. The

underlying mechanism is investigated through the perspective of deformation

recovery rate and ion migration behavior in the ionic hydrogels. As a result, the

developed piezoionic sensors are capable of distinguishing static forces in the

range of 0.1–5 s while monitoring dynamic force, breaking the limitations of

conventional self-powered pressure sensors that have trouble tracking static

forces. Furthermore, by utilizing the piezoionic effect to convert the touch

indentation into transverse gradient ionic potential, the constructed piezoionic

sensors achieve accurate monitoring of finger pressing position and sliding

trajectory. As a proof-of-concept, pattern unlocking in security authentication

is successfully validated based on the developed piezoionic sensors. This

design strategy of modulating ionic tactile sensor by crosslinking is expected

to provide a fresh path for the large-scale flexible human-machine interfaces.